There is a continuing need in clinical practice for valid and reliable instruments that measure an individual's subjective experience of pain. Recent standards issued by the Joint Commission on Accreditation of Healthcare Organizations state that pain is one of the vital signs that should be routinely assessed when an individual enters the health care system. The paper-and-pencil methods currently used in the clinic for this purpose are costly in terms of staff time and often produce time-delayed results. With the dramatic and ongoing improvement in computer technology, our ability to assess pain in a quantitative and efficient manner has greatly improved, The assessment battery under development in this Phase II proposal is referred to as the "Computer Assessment of Pain" (CAP). By dynamically interacting with visual displays, the patient indicates the intensity and emotional impact of pain, the word descriptors that best characterize pain and its emotional impact, and the precise location of pain on the body. The research objective is to examine the psychometric properties and clinical utility of CAP for patients in chronic pain. In Year 1 the method's test-retest reliability and validity will be investigated. In Year 2 the sensitivity of CAP will be examined by determining how well the instrument tracks relief from low back pain before and after epidural steroid injection. A Spanish version also will be developed and tested in Year 2. The main advantages of this new assessment suite are (a) ratio scale measures are obtained, (b) ratings of items are given in the context of other items, (c) dynamic adjustments and fine-tuning of ratings are possible, and (d) data collection and analysis is efficient and inexpensive. PROPOSED COMMERCIAL APPLICATION. The commercial goal is to replace paper-and-pencil methods with a computer-administered method that allows dynamic ratings of pain variables within the context of other variables. The software will be available for the two major computer platforms (Windows & Macintosh). As marketed in Phase III, the software package will be purchased by physicians, pain clinics and hospitals.